Control system



CONTROL SYSTEM.

Filed Sept. 21, 1939 Wah??? jzf.

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Patented July 8, 1941 CONTROL SYSTEM Robert H. Hill, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application September 21, 1939, Serial N o. 295,857

6 Claims.

The present invention relates to improved electrical means for moving a control element to predetermined positions. More particularly it relates to automatic tuning mechanism for radio receivers in which the tuning shaft is moved to any one of a plurality of predetermined positions corresponding to broadcasting station frequencies by station selector mechanism located at a distance from the automatic positioning (Cl. 25th-20) type, will be referred to in the course of the following description.

For a more complete understanding of the invention reference will be made to the single accompanying drawing showing the structure in diagrammatic form and the circuits for controlling and actuating the tuning shaft.

lctei'erring to the drawing by reference charactors, l designates a radio receiving set having mechanism. 1o a radio speaker (not shown) and a tuning shaft In automatic tuning mechanisms of the type 3 provided with `a conventional control knob 5 described it is necessary to provide means for lined thereto for manual rotation. A reversible reversing an electric motor to rotate a tuning electric motor l is operably connected to roshaft in either direction and to cause the shaft tate the tuning shaft by means of the gears 9 to be stopped accurately in one of a plurality and il lined respectively to a motor shaft I3 of positions in order to obtain sharp tuning. It is and to a hollow shaft It rotatably mounted on also necessary to provide a plurality of readily the tuning shaft 3 and having a clutch disc Il adjustable means for changing the positions at lXed tlleleto- Complementary Clutch diSC l9 which the shaft is to be stopped in order to obtain axially movable on and rotatable with the tuna diiferent selection of broadcasting frequencies to ing Shaft 3 iS normally held out of engagement suit the locality in which the receiver is operated. with the clutch disc Il but is movable into en- This adjustable feature is especially desirable for sagement With it by an 'electromagnetic Windreceivers installed in vehicles traveling between ing flXed thereto and liaVng end Connections 2| different localities. In prior'mechanisrns of ythis and 23- Tlle connection 2l iS connected to the type remote controlled mechanisms have been Ilnotol armature Winding by a conductor 25 and used in which electrically actuated mechanical the other connection 23 S groundeddetents were used for stopping rotation of the The motor l has a ConVentOnal armature shaft. These mechanisms included electrical winding, one side 2l of Which iS Connected to contact means movable by the detents to break ground and the other Side iS Permanently conelectrical circuits for the shaft driving means and nected internally to the conductor 25 and t0 were satisfactory for stopping the shaft in deftwo exciting field windings having Separate eX- inite positions butin case of binding of the deternal end Connections 29 and 3l extending t0 tents the electrical circuits were not interrupted Xed Contacts 33 and 35 of a relay indicated and failures of the electrical driving mechanism generally at 37- EXcltatOn of either of the eld occurred. windings causes opposite rotation of the motor The primary object of the present invention is Shaft l3- to provide a simplified remotely controlled auto- The relay 3l colnpliSeS tWO armatures 39 and matic tuning mechanism in Which angularly lll pvotally lnollnted at points 43 and 45 ntermovable and manually adjustable electric conmediate their ends on a stationary insulated tact mechanisms only are used to control the Support 4i and are connected together for si electrical driving means so that the tuning shaft multaneous parallel rocking movement about may be rotated in either direction to a, pluthese points by an insulated connecting rod 49 rality of predetermined positions. pivoted to each. A blade spring 5I having one Another object is to provide electrical means end llXed to the Support 4l and the other flXed for mechanically disengaging the electrical drvto the connecting rod All serves to hold both arng means from the tuning vshaft to stop it in a matures in their open circuit position with the precise angular position with no ovorrunning, armature 4l out of Contact With the fixed con- A further object is to provide separato enertacts 33 and 35 and the armature 39 out of gization means for the control circuits and the Contact With Xed contacts 55 and 6l to be circuit to the electrical driving means to insure 50 referred to Subsequently. The armature 4| is long Contact life, connected by a conductor 53 to one side of a Other objects of the invention and means by source of current or battery 55, the other side which the above objects are accomplished, as El of Which is grounded. Both ofthe armatures Well as the advantages derived by the use of 39 yand 4l are provided with contacts 59 lixed these improvements over prior devices of this 55 on opposite ends thereof. The armature 4l serves to energize the motor armature through either field connection 29 or 3| when either of the contacts 59 of the armature di is moved into contact with either of the fixed contacts 33 or .'55 located adjacent thereto. The armature 39 is connected to ground by a conductor Ci and serves to ground a conductor 63 included in the speaker circuit associated with receiver to mute the speaker when either of the contacts 59 of the armature 3Q makes contact with either of the fixed contacts 65 or 61, both of which are connected to the ground conductor 6|. Simultaneous parallel rocking movement of the armatures 3S and 4| in either direction about their pivots 43 and 45 respectively is accomplished by two relay electromagnets 69 and 1| located adjacent the ends of the upper armature which attract the respective ends thereof when energized individually and move both armatures in either direction. The relay eiectromagnets ES and 1| are separately connected to individual bus bars 13 and 14 by conductors 15 and 11 and have a common connection 19 extending between the opposite end of their individual windings which is connected to a bus bar 8| by a conductor 83.

Either of the relay electromagnets is excited from any one of a number of parallel branch circuits, three of which are shown, connected to a bus bar 85 which is connected to the battery 55. Any number of such circuits may be used. Each of these circuits is connected by conductors 81a, 81e and 81e to the bus bar 85 and include identical manually operable selector switches indicated generally at 89a, 89h and 89C which may be located at a distance from the receiver an motor and are provided with electromagnetic holding coils 91a-, 91h and 91C. Identical shaft positioning switches generally indicated at Ia,

|635 and |23c are also included in each of these x circuits. The selector switches and shaft positioning switches comprise identical parts which operate in like manner and the following description will therefore be confined to one of these circuits only which includes a single switch of each type.

The selector switch 89a consists of an armature Bla manually movable to bridge contacts 93a and 95o. An electromagnetic holding coil Sla located adjacent the armature Sia serves to atf tract and hold it in bridging relation with the contacts 93a and 95a when energized but it is incapable of attracting and moving the armature from its normal open position in which it is shown. One end 953e of the holding coil 91a is connected to ground and its opposite end |G|a is connected to the bus bar 8| to which the electromagnetic relay coils 89 and 1| are connected so that either of these electromagnetic relay coils and the holding coil 91a may be connected in series to ground through the end 99a of the holding coil 91a. Switch contact 93a is connected to the conductor 81a. and contact 95a is connected to a shaft positioning switch w3c by a conductor |Ua.

The shaft positioning switch |E3a comprises an insulating disc |01a having spaced arcuate contacts |53@ and |||a imbedded in the disc and having their external surfaces flush with the peripheral surface of the insulated segment H3G. of the disc separating the ends of these contacts. The disc 101e! is fixed to the tuning shaft 3 for rotation thereby and has three brushes |i5a, ||1a and ||8a suitably held in contact with its peripheral surface. The brush ||5a is connected to the conductor |05a and is supported on a brush holder |2|a provided with an arcuate slot |23a through which a stud |25a projects. The stud |25a is attached to a fixed support |21a and the brush and the brush holder may be angularly adjusted to any one of a plurality of angular positions with respect to the disc |01a and the fixed support |210i and may ce locked thereto by means of a nut |2910. threaded on the end of the stud |25a. In the position shown brush ||5a is in contact with the segment llaa only. The brushes ||1a and ||9a are spaced angularly to either side of the adjustabe brush ||5a and are suitably held in a fixed angular position so that each remains in electrical contact with the individual arcuate contacts |0911 and |||a for all angular positions of the disc and tuning shaft. The brush ||1c in contact with the arcuate contact la is connected to the bus 13 by a conductor |3|a and the brushHSa in contact with arcuate contact Illa is connected to the bus bar 14 by a conductor |23a. As the relay electromagnets 59 and 1| are connected separately to the bus bars 13 and 14 by conductors 69 and 1|, either of the electromagnets 6B or 1| may be energized through any of the shaft positioning switches 103e, |0317 and |030, depending upon the angular relation of the insulating disc segments l3a, H311 and ||3c and arcuate contacts adjacent thereto are in relation to the adjustable brushes w3c, |03?) and |03c when any one of the circuits in which these shaft positioning switches are connected is selectively connected to the battery upon closure of any one of the selector switches 89a, 89h or 89o.

The operation of the automatic tuning mechanism is as follows:

With the parts in the position shown when the selector switch 89h is closed a control circuit is completed through the following conductors: battery 55, conductors, v and 81h, contact 93o, selector switch armature 9|b, contact 95h, conductor |051), brush |I5b, arcuate contact |091), brush ||1b, conductor |3|'b, bus 13, conductor 15, relay electromagnet winding 69, conductors 19, 83, bus 8|, conductor |0Ib, electromagnet holding coil winding 91h and to ground through conductor 99D. Energization of the holding coil attractsrand holds the selector switch armature SIb in the closed position to maintain this circuit energized. `Energizati'onof the relay electromagnet E9 attracts and moves the left end of both relay armatures upward to establish the following connections. The relay armature 39 grounds conductor 63 of `the speaker circuit to mutethe speaker, not shownfand the 'relay armature 4| connects the motor 1 to the battery 55 by the following conductors: conductor r53, armature 4|, contacts 59 and 35, field conductor 3l and through the armature winding lto ground by the conductor 21. The parallel circuit connection 25 from the vmotor armature winding to the electromagnetic clutchwinding is also energized to cause `engagement of the tuning shaft disc I9 with the motor-driven disc |1.

Energization of the field conductor 3| causes the motor to rotate lthe tuning shaft counterclockwise as indicated Vby `the 'arrow on the disc |012), thereby causing the insulating segment ||3b to move toward the brush ||^5b and assume the same angular position with respect to the center line of the vshaft that the brush occupies which causes the control circuit to be opened and the motor and clutch circuits controlled thereby to open. The tuning shaft is thus rotated to a definite angular position and stopped by disengagement of the clutch mechanism. The tuning shaft which is mounted in the conventional manner and has the usual friction means associated therewith to prevent movement, stops instantaneously in this position and the motor armature and shaft having some inertia may continue to revolve, but as the clutch. is disengaged the shaft will not continue to overrun with the motor.

With the parts in the position shown, it is evident if the shaft positioning switch |030 is energized by its respective selector switch S30, the motor will rotate the shaft clockwise from the position yshown to a definite angular position corresponding to the angular position which the respective adjustable brush ||5c occupies. In this case, however, the other relay electromagnet will be energized by the conducto-rs bus 14, 'conductor |330, brush HSC, arcuate Contact |l|c which is now connected to the battery by the selector switch |03c and the parallel conductors as before enumerated but having a c subscript. The relay armatures 39 and 4| will now be moved in the opposite direction so that the field connections 29 will be energized and the tuning shaft will rotate clockwise as indicated by the arrow on the disc |`|c until the insulating segment |30 breaks all circuits by moving under the adjustable brush |5c thus stopping the tuning shaft in a different angular position.

It is evident from the above description that the stopping position of the tuning shaft is determined by the position of the adjustable brush and that the motor circuit connections controlled by any parallel control circuit are such that the shaft is rotated in either direction to a definite angular position which can be varied by moving this brush angularly with respect to any disc. The insulating segment is always rotated toward the movable brush from any angular position either side of the brush and it and the shaft is stopped at this position.

With this particular control consisting of only electrical contacts movable with respect to fixed and adjustably fixed contacts, any control circuit can be selectively energized by manually operable selector means which 'controls a separate motor circuit to cause rotation of the shaft in either direction to one of a plurality of predetermined positions Where the shaft will be automatically stopped. Each position can be set by tuning the receiver to a certain broadcasting fre quency by means of the tuning knobs and then moving the adjustable brush so that it is in mechanical contact with the insulating segment and out of electrical contact with the arcuate contacts adjacent thereto and then locking it in this position which is the position that brush ||5a and segment ||3a are shown in. As the control Icircuits are energized from the battery by a different circuit from the motor circuit all the contacts may be designed for low current flow to insure long life and trouble-free operation.

I claim:

1. In an automatic tuning mechanism for radio receivers comprising, a tuning shaft, an electric motor operably connected to drive the shaft, a source of current, a power circuit including said motor, said source of current and motor control means movable to establish forward and reverse driving connections to the motor but normally held in the open circuit position, and a control circuit separately connected to said source of current including electromagnetic means for moving said motor control means, manually operable control circuit closing means having electromagnetic holding means therefor and switch means driven by said tuning shaft having an open circuit position for a given angular position of the tuning shaft and closed circuit positions on either side of this position to connect one or the other of said electromagnetic means and said electromagnetic holding means with said source of current. i j,

2. In an automatic tuning mechanism for radio receivers comprising, a tuning shaft, an electric motor operably connected to drive the shaft, a source of current, a radio speaker circuit, a separate power circuit including the motor and the source of current, separate relay contacts in both of said above mentioned circuits normally biased to their open circuit position and movable simultaneously to ground the speaker circuit and to establish forward or reverse driving connections to the motor, a pair of electromagnets for moving said relay contacts and a control circuit separately connected to said source of current including said electromagnets, manually operable control circuit closing means and means operably connected to the tuning shaft for rotation thereby to open said control circuit in a definite angular position of the control shaft and to closev said circuit to energize one electromagnet or the other when moved to an angular position either side of this position to cause rotation of the shaft by the motor toward said denite angular position.

3. In an automatic tuning mechanism for radio receivers comprising, a manually rotatable tuning shaft, an electric motor for driving the shaft, means between the tuning shaft and motor engageable to cause rotation of the shaft by the motor, electromagnetic means for causing engagement of said means, a source of current, a circuit from said source of current to the motor, a circuit from the motor to the electromagnetic means, means in said motor circuit movable in either direction from its normal open circuit position to establish forward or reverse rotation of the motor and tuning shaft and to control energization of said electromagnetic means, separate electromagnets for moving said last mentioned means either way from its normal position, a plurality of control circuits lconnected to said source of current, each of said control circuits including said electromagnets, a manually operable selector switch for closing one of said control circuits, an electromagnetic holding coil for maintaining each switch in the closed position, and a contactor mechanism driven by said shaft to connect either of said electromagnets and said electromagnetic holding coils in the circuit for all angular positions of said tuning shaft either side of a definite angular position to cause rotation of the tuning shaft in either direction to the definite angular position at which said contactor mechanism opens said circuit to stop rotation of said tuning shaft.

4. In an automatic tuning mechanism for radio receivers comprising, a manually rotatable tuning shaft, a reversible electric driving motor, a clutch connected between the tuning shaft and the motor engageable to cause rotation of the shaft by the motor, a clutch engaging circuit connected to the motor and including an electromagnetic winding for engaging said clutch when the motor is energized, a source of electrical energy, a motor energizing circuit, means in said motor energizing circuit movable to establish forward and reverse driving connections of the motor and to normally open either or both of these connections, a control circuit including forward and reverse electromagnetic attracting means for moving said movable means included in the motor energizing circuit, a plurality of pairs of spaced contacts fixed to the tuning shaft for rotation therewith, conductors connected between each contact and each forward and reverse electromagnetic means and a plurality of energizing circuits for each pair of contacts, each including a brush angularly adjustable into contact with either contact of a pair, and a selector switch connected in series between each brush and said source ol energy and manually movable to complete one of said energizing circuits and said control circuit switch and each brush to cause said tuning shaft to be revolved to one of a plurality oi predetermined angular positions, each of which may be varied by the adjustably movable brush.

5. In an automatic tuning mechanism for radio receivers comprising, a tuning shaft, an electric motor connected to drive the shaft, a source of current, circuit to the motor from the source of current, a relay armature in said circuit normally biased to the open circuit position and movable to establish forward and reverse driving connections to the motor, separate electromagnetic means to move said relay armature, a separate control circuit including the electromagnetic means, a plurality of control switches for said circuit, each of said switches comprising a rotatable insulating element attached to and driven by the tuning shaft, spaced arcuate contact on said element, conductors between each contact and each electromagnetic means, a brush angularly adjustable with respect to said contacts to make contact with either contact of said rotatable element or with a space therebetween, a plurality oi parallel energizing circuits from said source of current to each of said brushes and a manually operable switch normally biased to a neutral or open position included in each of the parallel energizing circuits and movable to its closed position for selectively energizing one of said control switches to cause rotation of the motor and tuning shaft to a definite angular position set by the angularly adjustable brush in the circuit so energized, each of said manually operable switches having electromagnetic holding means connected in series with said electromagnetic means or holding said switches in their closed position until said shaft is indexed to a denite position, whereupon said switches return to a neutral or off position.

6. In an automatic tuning mechanism for radio receivers comprising, a manually rotatable tuning shaft, an electric motor for driving said shaft, a clutch between said shaft and said motor engageable to cause rotation of the tuning shaft, electromagnetic means for engaging said clutch, a circuit from said motor to the electromagnetic means to energize said electromagnetic means with the motor, a source of current, a motor circuit connected to said source including means for controlling forward or reverse operation of the motor, said means including xed contacts and an armature normally held out of contact with the fixed contacts but movable in opposite directions into contact therewith to establish forward or reverse driving connections of the motor and engagement of said clutch to cause rotation of the tuning shaft in either direction, a separate control circuit for said motor circuit connected to said source including a pair of electromagnets ior attracting and moving said armature in opposite directions, and contact means operably connected to the tuning shaft for rotation thereby to complete said control circuit through one or the other of said electrcmagnets for all angular positions thereof except a definite angular position at which the control circuit is opened to stop rotation of the tuning shaft by opening of the motor circuit and disengagement of the clutch.

ROBERT H. HILL.

CERTIFICATE CF CORRECTION.

Patent No. 2,2h8,55o. I July, 19ML ROBERT H. HILL.

It ie hereby certified 'that error appears in -the'printed specification o' the above numbered ypensent requiringl coreotion ae follows: Page 1L, first column; lines 19 to 22 inclusive, ciaimlh' strike out thewo'ras 'switch and each brush to 'cause :saidv tuning shaft to be revolved to. one of a plurality of predeennined angular positions, l.each of which maybe varied py the ad.-

jilsjgbly vmovifolge and` fbhat the lsaid Letters Patent should be read with this correction therein that the same may conform to the record of the case inthe Patent Office'. v signed and @Balea this 19m day ofiugust, A. D. 19m.A

y Hearn'y,y Van Arsdele, Acting Commissioner of Patents.

v RTIHCMEOF CORRECTION. patennuo. 2,211,8,35o Jgiy, 19m..y

' v ROBERT H. HILL. v

It isv hereby certifisdthat error appears in theprin'ed specifiation di the abovs -rmmberedv patent requiringy cori-'action as follows: Page li, first Colm; 1ine's19 to 22 inclusive, claimh; strike dut the'words *switch and eoh brush to ause said tuning shaft to. be revolved to. ons of a plrglity of prsclelerfniecl anglg psitionslsachof which maybe vried p'y the ad- `311ssa1 iy @visie s rusiy; an@ hating-said Letters Patent 'Shouldbe read-with this corre'ction therein that the same may 'onfqrm tQth'e rcord of the case in the Patent office'.

Signed and sealed this 19th day of `August, D.A 1914.1.

A v Henry van Arsdl; Acting Commissioner of Patents. 

